The long term objective of this project is to develop a practical Volume flow measuring Doppler system for quantification of blood velocities and flows throughout the body. Health care applications of such a device include evaluation of arterial occlusive disease, venous occlusive disease, extracranial arterial occlusive disease, and monitoring of cardiac output and organ perfusion. During Phase I, we will develop through both mathematical simulation and experimentation practical transducer designs to measure arterial blood velocity and flow. The electronic circuitry and computer software to implement the angle independent Doppler will be designed and tested. A prototype angle independent Doppler system suitable for use in the clinical setting will be designed and constructed. In Phase II clinical studies will be initiated to demonstrate the effectiveness of angle independent Doppler velocimetry for blood flow measurement, and to identify key application areas. The prototype system will be further refined to a practical unit suitable for commercial application.